SYNOPSIS OF GENERA. 
xlix 
This genus is represented by a single 
species which demonstrates the early ap¬ 
pearance of the true limuloid Crustacea. It 
is probable that its nearest known ally is the 
Neolimulus falcatus, Woodward, from the Upper 
Silurian of Lanarkshire. The latter fossil is 
regarded by Packard (Mem. Nat. Acad. Sci., p. 
151, 1886), as not referable to the Xiphosura, 
and, together with the genera Bunodes, 
Pseudoniscus and others are made to constitute 
a distinct group {suborder, Packard), Synzipho- 
SURA. This separation is made principally on 
the ground that in all these forms the abdomi¬ 
nal segments are free and not coalesced as in Neolimulus faiLtus, Woodward. 
Limulus. It may be questioned whether the non-anchylosis of the segments 
has been satisfactorily demonstrated in Neolimulus, or if so, whether a division 
of so high value as a sub-order is wisely established upon a single larval 
character. 
E U R Y P T E R I D A . 
Family, Eurypterid^. 
Genus EURYPTERU S, Dekay. 1825. 
1825. Eurypterus, Dekay. Ann. Lyceum Nat. Hist. New York. 
1831. Eidothea, Scoulbr. Edinbui-g Journ. Nat. and Geograph. Science. 
1835. Eurypterus, Habi.an. Med. and Phys. Researches. 
1835. Euryptents, Harlan. Trans. Geol. Society Penna. 
1835. Eurypterus, Bronn. Lethaja geognostica. 
1836. Eurypterus, Hibbbrt. Trans. Roy. Soc. Edinburg. 
1839. Eurypterus, Fischer. Bull. de. la Soc. Imji. des Naturalistes de Moscou. 
1841. Ehiryptei’us, Conrad. Ann. Rept. Pal. New York. 
1843. Euryp>terus, Vanuxem. Geol. N. Y.; Rept. Third Dist. 
1843. Eurypterus, Burmeistr. Oi-gan. der Trilobiten. 
1848. Eurypterus, C. F. Rcemer. Palieontographica. 
1850. Eurypterus, C. F. Rcemer. Lethsea geognostica. 
1853. Eurypterus, Dana. Crust. U. S. Expl. Exped. Capt. Wilkes. 
1854. Eurypterus, Eichwai.d. Bull, de la Soc. Imp. des Naturalistes de Moscou. 
1855. Eui-ypte^'us, McCoy. British Palieoz. Fossils. 
1855. Lepldoderma, Reuss. Denkschr. der Akad. Wissensch. Wien. 
1856. Eurypterus, Huxley. Quart. Jour. Geol. Soc. 
